1. Field of the Invention
The invention relates to an apparatus for plasma chemical vapor deposition (hereinbelow, chemical vapor deposition is referred to as CVD). More particularly, the invention relates to a plasma CVD apparatus in which a silicide or metal film for a circuit pattern is formed on a substrate for an integrated circuit.
2. Description of the Prior Art
A low temperature plasma CVD apparatus has often been employed to form a silicide or metal film to be utilized as a gate electrode or wiring material for an integrated circuit.
Such an apparatus employs a gas of a compound which is liquid at room temperature, such as an inorganic fluoride compound, molybdenum fluoride (MoF.sub.6), or tungsten fluoride (WF.sub.6), or trimethyl aluminum Al(CH.sub.3).sub.3, or titanium tetrachloride (TiCl.sub.4). These compounds vaporize at room temperature and, thus, do not have to be heated. Gases of these compounds, however, may often condense on the wall of the gas feeding pipe provided in the apparatus, thus deteriorating the reproducibility in plasma CVD.
In the case of the use of a gas of a compound which is solid at room temperature, such as aluminum chloride (AlCl.sub.3), molybdenum chloride (MoCl.sub.5), tungsten chloride (WCl.sub.5 or WCl.sub.6), or another inorganic chloride compound, the gas of the compound may solidify at the middle of the gas feeding pipe of the apparatus, thus deteriorating the reproducibility in plasma CVD or blocking the gas feeding pipe.
Because of the above, a conventional plasma CVD apparatus can only use a limited range of compounds for the feeding gas. This often prevents obtaining a deposited film of a satisfactory adhesion strength or good quality.